Page:The New International Encyclopædia 1st ed. v. 05.djvu/184

COLLISIONS OF VESSELS. 152 COLLOIDS. as on land. In both the United Stales and Great Britain reguhitions are laid down which, though not having the force of law, are recog- nized by the admiralty courts, and govern the decisions in cases of collisions. In general, they are analogous to the rules observed by pedes- trians in crowded tlioroughfares, and by vehicles on highways. It is at night that the danger of collision is" greatest; and hence the necessity for a well-arranged systcip of lights and other pre- cautions. Of 3575 casualties of all kinds on and near the coasts of the United Kingdom in 1880-81, 713 were due to collisions: of these 09 resulted in total loss. The transatlantic steam- ers running between Queenstown, or the Chan- nel ports, and Xew York have adopted the 'lane system,' first advocated by Lieutenant ilanry, U. S. X., and afterwards developed by the Hydro- graphic Office, U. S. Xavy, and approved by the Marine Conference held at Washington in 1889. This consists in the assignment of a definite lane or track to each separate line of steamships, along which route their vessels are required to maintain their course. It has been held by American courts that, if a collision happens without fault, and no blame can be charged to those in charge of either vessel, each party nuist bear its own loss. In case both parties' are at fault, neither can have relief at common law-; but maritime courts aggregate the damage to both vessels and their cargoes, and divide the amount equally between the two. In case of inscrutable fault, that is, by a faiilt of those in charge of one or both vessels, and yet under such circumstances that it is impossible to learn who is at fault, the rule of equal division is also adopted. Where the fault is on the ]iart of one vessel and no fault on the other, the owners of the vessel at fault must bear their own loss, and are also liable for the damage to the other vessel. In some cases the personal liability of owners is limited to the value of the vessel and freight. Strict laws, rules, signals, etc., are adopted by all nations to prevent collisions. (See XAaGATiox L.ws.) But, no matter how exacting may be the rules, cases will occur when their following would result in disaster. Xo vessel should unneces- sarily incur the probability of collision by strict adherence to the rules. If it is clearly in the power of one vessel to avoid collision by depart- ing from the rules, .she will be held bound to do so; but a vessel is not required to depart from the rule when she cannot do so without danger. A proper lookout must be kept : the absence of such a lookout is in itself evidence of liegligence. In some cases certain lights must he" kept. Losses of a vessel injured by a col- lision are within the ordinary policy of insur- ance; but when the collision is the fault of the insured vessel, or of both vessels, the insurer is not ordinarily liable for injury done to the other vessel which may be decreed against the vessel insured, although recent policies provide that the insurer shall be liable in such case. COLLO'DION (Xeo-Lat.. from Gk. xoXXiiSTjs, I;oIl6dcs, glue-like, from KiSXXa, koUa, glue -f eiSos. eidos. form). A solution of pyroxylin in a mixture of alcohol and ether. For its man- ufacture a convenient form of cellulose, such as cotton wool, is immersed in a mixture of nitric and sulphuric acid with a little water, or in a mixture of potassium nitrate with sulphuric acid. The resulting product is washed in water and dried. The pyroxylin thus obtained is then treated with ether, to which alcoliol is added luitil the substance is completely dissolved. The solution is a clear, colorless liquid that does not mi.x with water or alcohol, but readily mixes with ether; when exposed to the air it dries up, leaving a transparent film, which becomes elec- tric by friction and may be exploded by heat, pressure, or percussion, ili.xed with substances sensitive to light, collodion is extensively used in photography ; the mixture is spread over a glass plate, on which it forms, when dried, a sensitive film. Collodion is also used in surgery, the tenacious and transparent film left by its evaporation preventing the access of air to the injured surface and protecting it from infection. Pills and other medicinal preparations may be coated with it so as to render them tasteless. Among the medicinal collodions that are official is hlistering or vesicating collodion, which con- sists of cantharides dissolved in collodion; the solution is applied to the skin when it is desired to raise a blister. Wood, paper, and fabrics may be rendered waterproof by being covered with collodion. Small balloons are made from it by pouring a solution into a flask of the desired dimensions, which is then turned about so as to spread the liquid uniformly over the surface, and then inverted to allow the excess to run out. The solvent is then allowed to evaporate, and the edges of the remaining film are loosened from the glass by attaching a glass tube to the neck of the flask and withdrawing the air. whereupon the collodion balloon detaches itself, contracts, and is easily withdrawn. See also Cellulose. COL'LOIDS (from Gk. K6a, koUa, glue + elSos, cidos, form). A name applied by Graham to a group of substances, including ferric oxide, alumina, silicic acid, starch, dextrin, gum, albu- min, gehitin, tannin, caramel, agar-agar, and others, These substances, though not by any means belonging to the same class chemically, behave alike in certain respects when obtained in solution in water or in some other solvent. In the first place, they diffuse, when dissolved, verv much more slowly than most other sub- stances ordinarily met with. In the second place, their presence in solution has scarcely any effect on the freezing-point or .on the vapor- tension of the solvent, while most other sub- stances have the effect of notably lowering both the freezing-point and the vapor-tension. Again, colloids often spontaneously deposit from their solutions in the form of gelatinous masses that cannot, in many cases, be re-dissolved and that usually retain mechanically a large amount of water. Such "gelatinized solutions' are now used for a variety of purposes in the arts, advan- tage being taken of the mass being in a semi- solid condition, while the liquid retained by it may be used for the same purposes as when in the free state ; such masses are used in photog- raphy by the "dry' process, in making 'dry* electric batteries, in the manufacture of certain valuable explosives, etc. In scientific researches gelatinized solutions are now used for the pur- pose of studying the relative rates at w-fiieh various substances diffuse in water. For this purpose it is important that the solutions should remain absolutely undisturbed for a considerable length of time, and this is accomplished best by